Add rectangles exercise (#83)

Author: keiravillekode

config.json

@@ -529,6 +529,14 @@
         "prerequisites": [],
         "difficulty": 7
       },
+      {
+        "slug": "rectangles",
+        "name": "Rectangles",
+        "uuid": "93586bb2-3ee5-425f-ba18-ca9f1eecb17a",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 7
+      },
       {
         "slug": "dominoes",
         "name": "Dominoes",

exercises/practice/rectangles/.docs/instructions.md

@@ -0,0 +1,63 @@
+# Instructions
+
+Count the rectangles in an ASCII diagram like the one below.
+
+```text
+   +--+
+  ++  |
++-++--+
+|  |  |
++--+--+
+```
+
+The above diagram contains these 6 rectangles:
+
+```text
+
+
++-----+
+|     |
++-----+
+```
+
+```text
+   +--+
+   |  |
+   |  |
+   |  |
+   +--+
+```
+
+```text
+   +--+
+   |  |
+   +--+
+
+
+```
+
+```text
+
+
+   +--+
+   |  |
+   +--+
+```
+
+```text
+
+
++--+
+|  |
++--+
+```
+
+```text
+
+  ++
+  ++
+
+
+```
+
+You may assume that the input is always a proper rectangle (i.e. the length of every line equals the length of the first line).

exercises/practice/rectangles/.meta/config.json

@@ -0,0 +1,17 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "rectangles.fut"
+    ],
+    "test": [
+      "test.fut"
+    ],
+    "example": [
+      ".meta/example.fut"
+    ]
+  },
+  "blurb": "Count the rectangles in an ASCII diagram."
+}

exercises/practice/rectangles/.meta/example.fut

@@ -0,0 +1,25 @@
+local def is_vertical_line (strings: [][]u8) (bottom: i64) (top: i64) (left: i64): bool =
+  let result = loop result = true for row in top...bottom do
+    result && (strings[row][left] == '|' || strings[row][left] == '+')
+  in
+    result
+
+def rectangles [m] [n] (strings: [m][n]u8): i32 =
+  let result = loop result = 0 for bottom in 1..<m do
+    let result = loop result = result for right in 1..<n do
+      if strings[bottom][right] != '+' then result else
+      let (result, _) = loop (result, top) = (result, bottom - 1) while top >= 0 do
+        if strings[top][right] == '|' then (result, top - 1) else
+        if strings[top][right] != '+' then (result, -1) else
+        let (result, _) = loop (result, left) = (result, right - 1) while left >= 0 do
+          if is_vertical_line strings bottom top left then (result + 1, left - 1) else
+          if (strings[bottom][left] == '-' || strings[bottom][left] == '+') && (strings[top][left] == '-' || strings[top][left] == '+') then (result, left - 1) else
+          (result, -1)
+        in
+          (result, top - 1)
+      in
+        result
+    in
+      result
+  in
+    result

exercises/practice/rectangles/.meta/tests.toml

@@ -0,0 +1,54 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[485b7bab-4150-40aa-a8db-73013427d08c]
+description = "no rows"
+include = false
+
+[076929ed-27e8-45dc-b14b-08279944dc49]
+description = "no columns"
+include = false
+
+[0a8abbd1-a0a4-4180-aa4e-65c1b1a073fa]
+description = "no rectangles"
+
+[a4ba42e9-4e7f-4973-b7c7-4ce0760ac6cd]
+description = "one rectangle"
+
+[ced06550-83da-4d23-98b7-d24152e0db93]
+description = "two rectangles without shared parts"
+
+[5942d69a-a07c-41c8-8b93-2d13877c706a]
+description = "five rectangles with shared parts"
+
+[82d70be4-ab37-4bf2-a433-e33778d3bbf1]
+description = "rectangle of height 1 is counted"
+
+[57f1bc0e-2782-401e-ab12-7c01d8bfc2e0]
+description = "rectangle of width 1 is counted"
+
+[ef0bb65c-bd80-4561-9535-efc4067054f9]
+description = "1x1 square is counted"
+
+[e1e1d444-e926-4d30-9bf3-7d8ec9a9e330]
+description = "only complete rectangles are counted"
+
+[ca021a84-1281-4a56-9b9b-af14113933a4]
+description = "rectangles can be of different sizes"
+
+[51f689a7-ef3f-41ae-aa2f-5ea09ad897ff]
+description = "corner is required for a rectangle to be complete"
+
+[d78fe379-8c1b-4d3c-bdf7-29bfb6f6dc66]
+description = "large input with many rectangles"
+
+[6ef24e0f-d191-46da-b929-4faca24b4cd2]
+description = "rectangles must have four sides"

exercises/practice/rectangles/rectangles.fut

@@ -0,0 +1 @@
+def rectangles (strings: [][]u8): i32 = ???

exercises/practice/rectangles/test.fut

@@ -0,0 +1,64 @@
+import "rectangles"
+
+-- no rectangles
+-- ==
+-- input  { [" "] }
+-- output { 0 }
+
+-- one rectangle
+-- ==
+-- input  { ["+-+", "| |", "+-+"] }
+-- output { 1 }
+
+-- two rectangles without shared parts
+-- ==
+-- input  { ["  +-+", "  | |", "+-+-+", "| |  ", "+-+  "] }
+-- output { 2 }
+
+-- five rectangles with shared parts
+-- ==
+-- input  { ["  +-+", "  | |", "+-+-+", "| | |", "+-+-+"] }
+-- output { 5 }
+
+-- rectangle of height 1 is counted
+-- ==
+-- input  { ["+--+", "+--+"] }
+-- output { 1 }
+
+-- rectangle of width 1 is counted
+-- ==
+-- input  { ["++", "||", "++"] }
+-- output { 1 }
+
+-- 1x1 square is counted
+-- ==
+-- input  { ["++", "++"] }
+-- output { 1 }
+
+-- only complete rectangles are counted
+-- ==
+-- input  { ["  +-+", "    |", "+-+-+", "| | -", "+-+-+"] }
+-- output { 1 }
+
+-- rectangles can be of different sizes
+-- ==
+-- input  { ["+------+----+", "|      |    |", "+---+--+    |", "|   |       |", "+---+-------+"] }
+-- output { 3 }
+
+-- corner is required for a rectangle to be complete
+-- ==
+-- input  { ["+------+----+", "|      |    |", "+------+    |", "|   |       |", "+---+-------+"] }
+-- output { 2 }
+
+-- large input with many rectangles
+-- ==
+-- input  { ["+---+--+----+", "|   +--+----+", "+---+--+    |", "|   +--+----+", "+---+--+--+-+", "+---+--+--+-+", "+------+  | |", "          +-+"] }
+-- output { 60 }
+
+-- rectangles must have four sides
+-- ==
+-- input  { ["+-+ +-+", "| | | |", "+-+-+-+", "  | |  ", "+-+-+-+", "| | | |", "+-+ +-+"] }
+-- output { 5 }
+
+let main (strings: [][]u8): i32 =
+  rectangles strings

generators/exercises/rectangles.py

@@ -0,0 +1,12 @@
+def gen_test_case(prop, description, inp, expected, f):
+    strings = str(inp["strings"]).replace("'", '"')
+
+    f.write(f"-- {description}\n")
+    f.write("-- ==\n")
+    f.write("-- input  { " + strings + " }\n")
+    f.write("-- output { " + str(expected) + " }\n\n")
+
+
+def gen_main(f):
+    f.write("let main (strings: [][]u8): i32 =\n")
+    f.write("  rectangles strings\n")